Interior member having an airbag door section for use in vehicles, and its molding method

ABSTRACT

A tear portion is formed at a substantially center portion in a longitudinal direction and at both end portions in a lateral direction of an air bag door portion of an instrument panel so as to be formed in an H shape in a plan view. In the air bag door portion, protrusions are protruded downward at positions at both sides in a longitudinal direction of an automotive vehicle having therebetween a center portion of the tear portion, these protrusions being integrally formed with the air bag door portion. Accordingly, it is structured such that during expansion of the air bag body, the expanding air bag body abuts lower surfaces of the protrusions, so as to press the protrusions upward. Therefore, even in a case wherein the air bag door portion and the main body portion of the trim member for the automotive vehicle are formed of the same resin, a quality of an outer appearance is not deteriorated, and a break force of a break portion of the air bag door portion is reduced to a desired value.

This is a Division of application Ser. No. 09/194,355 filed Nov. 20,1998 now U.S. Pat. No. 6,612,607, which in turn is a National Stage ofPCT/JP98/01207 filed Mar. 20, 1998. The entire disclosure of the priorapplications is hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

Conventionally, as an interior member of an automotive vehicle having anair bag door portion such as an instrument panel, a door trim, a centerpillar and the like, there has been known a structure described inJapanese Patent Application Laid-Open (JP-A) No. 8-192666.

In the instrument panel having the air bag door portion disclosed in theabove publication, a main body portion of the instrument panel and theair bag door portion are integrally formed by so-called dual-injectionmolding (double injection molding) wherein the air bag door portion (anopening portion) is injection molded with a thermoplastic elastomer,after a main body portion of the instrument panel having an openingportion for the air bag door is injection molded with a thermoplasticresin. Further, as a popularly known structure, there is an instrumentpanel to which an independent air bag door (injection molded with athermoplastic elastomer) is later attached.

However, in the instrument panel having the air bag door portionmentioned above, in a case wherein the whole of the instrument panel isconstructed of the same resin without replacing the resin of the air bagdoor portion with the resin of the main body portion, on the basis ofcharacteristics of the resin in the main body portion, the rate ofelasticity of the resin in the main body portion is 6 to 7 times higherthan the rate of elasticity of the resin (TPO) in the air bag doorportion, and the tensile strength in the main body portion is 1.5 to 2times higher than the tensile strength in the air bag door portion;thus, the break force of a portion for expansion formed in the air bagdoor portion, an H-shaped break portion (a tear portion), for example,becomes higher in a case of the same thickness, so that it is hard forthe air bag door portion to expand, and moreover, a hinge portion maybreak during expansion. If in order to solve this problem, the thicknessof the resin in the break portion is made too thin, underfill,oil-can-like-feeling and deformation are generated. Particularly, in ahard resin instrument panel, since unevenness appears in a periphery ofthe thin portion at an outer appearance side due to weld shrinkage, anundulation and the like, the quality of the appearance of outer islowered.

Further, in order to achieve a state wherein both a line of the breakportion and an outer periphery of the air bag door portion arecompletely invisible from the outer appearance side (an invisible type),there is a method of making the break portion thick during molding andthen cutting the break portion through a later process. However, in thismethod, it is very difficult to make the line in the break portioninvisible while maintaining a predetermined break force. That is, whenthe thickness of the resin is made thin, the line and the undulation inthe break portion are seen from the outer appearance side even in a casewherein a relief groove is provided, so that the quality of the outerappearance can not be maintained, and the thickness of the resin can notbe made sufficiently thin.

When it is difficult to expand the door portion due to the increasedbreak force required during expansion at the break portion (tearportion), which is formed at the air bag door portion, and in order toameliorate this the thickness of the resin in the break portion is madetoo thin, the thin portion becomes visible from an outer side and so thequality of the exterior appearance deteriorates; this deficiency is alsogenerated with respect to: a break portion of an interior member of anautomotive vehicle (vehicle interior member) such as an instrumentpanel, door trim, center pillar, or the like, wherein the interiormember is integrally formed in accordance with dual-injection molding,using different resins for the main body portion of the vehicle interiormember and for the air bag portion; and a break portion of a vehicleinterior member wherein the vehicle interior member is obtained byintegrally assembling the air bag door portion and the main body portionof the instrument panel by means of a locking hook, a screw or the like,after independently molding the air bag door portion and the main bodyportion of the instrument panel.

As for technologies relating to the present invention, there are:Japanese Patent Application Laid-Open (JP-A) Nos. 3-281457 and 7-179161in which stress is concentrated at a foaming layer and a skin in adoor-integral foaming instrument panel during an initial period ofexpansion, Japanese Patent Application Laid-Open (JP-A) No. 2-147452 inwhich a bead is formed along a tear portion in a later attached resindoor, Japanese Patent Application Laid-Open (JP-A) No. 5-185898 in whicha blade is set at a distal end of a door metal plate insert in adoor-integral foaming instrument panel, Japanese Patent ApplicationLaid-Open (JP-A) No. 7-291078 in which a hinge portion is reinforced ina hard instrument panel obtained by integrally molding a door portionand a main body of the instrument panel, Japanese Patent ApplicationLaid-Open (JP-A) No. 8-290749 in which a hinge portion is reinforced ina skin instrument panel obtained by integrally molding a door basemember and an instrument panel base member, Japanese Patent ApplicationLaid-Open (JP-A) No. 2-283546 in which a rib applying maximum shearingforce to a tear portion of an independent door is integrally formed,Japanese Patent Application Laid-Open (JP-A) No. 2-109848 in which at acan lid, a thin line is formed in a resin layer so as to surround anopened portion and a weld line is set on the thin line, Japanese PatentApplication Laid-Open (JP-A) No. 7-291078 in which a reinforcing memberis thermally caulked on a reverse face of a door portion in a resininstrument panel and a notch is formed on a tear line of the doorportion, and Japanese Patent Application Laid-Open (JP-A) No. 8-20040 inwhich a different kind of resin is injected by shielding a metal moldcavity by means of a shielding core so as to perform a core-backimmediately before the injection is completed.

SUMMARY

The present invention has been made taking the above facts intoconsideration, and an object of the present invention is to obtain aninterior member for an automotive vehicle having an air bag door portionin which the quality of the outer appearance is not deteriorated and thebreak force of a break portion in the air bag door portion can bereduced to a desired value even in a case of molding the air bag doorportion and a main body portion of the trim member for the automotivevehicle with the same resin.

A first aspect of the present invention, there is comprises: a tearportion formed in the air bag door portion; and push-up means forpushing up a portion at both sides or one side of the air bag doorportion having therebetween a center portion of the tear portion when abag body of the air bag is expanded.

Accordingly, an impact load from the bag body of the air bag isconcentrated at the center portion of the tear portion when the bag bodyof the air bag is expanded, and the center portion of the tear portionis smoothly broken. As a result, since the tear portion can be easilybroken even when the thickness of the tear portion is large, it ispossible to devise to reconcile expansion performance and the quality ofthe outer appearance (making invisible). Further, since the tear portionis broken first, a load at the hinge portion in the air bag door portioncan be lightened. Still further, since the air bag door portion can bemade of a hard material with high rigidity, an oil-can-like-feeling anddeformation can be prevented.

Further, a second aspect of the present invention, comprises: a tearportion formed in the air bag door portion; and a door hinge portionprotecting plate disposed below the air bag door portion, protrudingtoward a side of the tear portion rather than toward a hinge portion ofthe air bag door portion and having a high break force.

Accordingly, since the door hinge portion protecting plate is provided,the bag body of the air bag is prevented from being directly abuttingthe hinge portion of the air bag door portion when the air bag body isexpanded, so that the hinge portion of the air bag door portion can beprevented from being broken by the bag body of the air bag. Further,since the hinge portion of the air bag door portion can be protected,breakage can be made with relative ease in the tear portion having a lowstrength.

Still further, a third aspect of the present invention comprises: aresin fluidizing boundary is set at a core back area, which is forforming a tear portion when the air bag door portion is expanded; and aline of the tear portion is not seen from a side of an outer appearance.

Accordingly, the break force in the break portion can be lowered to adesired value due to a reduction of strength caused by the resinfluidizing boundary, by setting the resin fluidizing boundary in thecore back area for forming the break portion when the air bag doorportion is expanded. Further, since it is not necessary to make theresin thickness of the break portion significantly thin, the line in thebreak portion can be made in a state of being fully invisible from theside of the outer appearance, so that the quality of the outerappearance can be prevented from being lowered, heat resistance andaging performance is improved, and support and surface rigidity of awhole of the air bag door portion can be also improved.

Furthermore, in a fourth aspect of the present invention, in the firstaspect, the push-up means at a position at both sides or one side of theair bag door portion having therebetween a center portion of the tearportion is a protrusion which is integrally provided with the air bagdoor portion and which protrudes downward.

Accordingly, the impact load from the bag body of the air bagmomentarily acts on the portion when the bag body of the air bag isexpanded, and breakage is smoothly performed from the center portion ofthe tear portion. Further, it is possible to devise to reconcile thequality of the outer appearance and expansion performance through asimple structure in which the portion is merely provided in the air bagdoor portion.

Moreover, in a fifth aspect of the present invention, in the firstaspect, the push-up means is disposed at a lower side of the air bagdoor portion, and is a metal plate providing a protrusion at at leastone of an upper surface or a lower surface of a distal end portion thatabuts, when the air bag body is expanded, a position at both sides orone side of the air bag door portion having therebetween the centerportion of the tear portion.

Accordingly, due to the metal plate, the impact load from the bag bodyof the air bag acts on the center portion of the tear portion in aconcentrated manner when the bag body of the air bag expands, so thatbreakage is smoothly performed from the center portion of the tearportion. As a result, it is possible to devise to reconcile the qualityof the outer appearance and expansion performance. Further, thestructure can be applied to a conventional trim member for an automotivevehicle by using the metal plate.

Further, in a sixth aspect of the present invention, in the firstaspect, the push-up means is disposed at a lower side of the air bagdoor portion and is a metal plate providing a narrow protrusion at anupper surface of a distal end portion that abuts, when the air bag bodyis expanded, a position at both sides or one side of the air bag doorportion having therebetween the center portion of the tear portion, whenthe air bag body is expanded.

Accordingly, due to the protrusion of the metal plate, the impact loadfrom the bag body of the air bag acts on the center portion of the tearportion in a concentrated manner when the bag body of the air bagexpands, so that breakage is smoothly performed from the center portionof the tear portion. At this time, the narrow projection is provided onthe upper surface of the front end portion of the metal plate, wherebyit is possible to reliably break from the center portion of the tearportion even when the upper surface of the bag body of the air bag is ofan uneven shape during an initial period of expansion.

Still further, in a seventh aspect of the present invention, in thefirst aspect, the push-up means is disposed at a lower side of the airbag door portion and is a metal plate providing a distal end portionthat abuts, when the air bag body is expanded, a portion at both sidesor one side of the air bag door portion having therebetween the centerportion of the tear portion when the air bag body is expanded; a hingeportion of the metal plate is off set toward a side of the tear portionrather than toward the hinge portion of the air bag door portion; andwith respect to the hinge portion of the metal plate, a tear portionside position has more rigidity than a fixing portion of the metal plateand a hinge portion of the metal plate.

Accordingly, due to the distal end portion of the metal plate the impactload from the bag body of the air bag acts on the center portion of thetear portion in a concentrated manner when the bag body of the air bagexpands, so that breakage is smoothly performed from the center portionof the tear portion. As a result, it is possible to devise to reconcilethe quality of the outer appearance and expansion performance. Further,since it is possible due to the metal plate to prevent the bag body ofthe air bag from being directly abutting the hinge portion of the airbag door portion when the bag body of the air bag is expanded, it ispossible to prevent breakage of the hinge portion of the air bag doorportion due to the bag body of the air bag.

Furthermore, in an eighth aspect of the present invention, in the firstaspect, a hinge portion of the air bag door portion is formed as a thinportion having a predetermined thickness across a predeterminedlongitudinal width and is adjacent to a case mounting portion, and agroove as a bending point is set in the middle of the longitudinal widthof the thin portion.

Accordingly, since the bending point can be set apart from the casemounting portion at which the plate thickness suddenly changes, the rateof local expansion (the rate of the extension of the skin layer) due tobending can be reduced. Further, since the groove is formed at thebending point, the surface expansion length of the bending portion canbe increased and the actual expansion rate can be made small, so that itis possible to effectively prevent the hinge portion from breakage dueto bending when the bag body of the air bag is expanded.

Moreover, in a ninth aspect of the present invention, in the firstaspect, the air bag door portion and the main body portion areintegrally formed of the same hard resin material, or separately formed.

Accordingly, even in a case wherein the air bag door portion and themain body portion are integrally or separately formed of the same hardresin material, the impact load from the bag body of the air bag isconcentrated at the center portion of the tear portion, so that breakageis smoothly performed from the center portion of the tear portion. As aresult, since breakage is easily performed even when the thickness ofthe tear portion is thick, it is possible to reconcile a expansionperformance and a quality of an outer appearance (making invisible).Further, since the tear portion is broken first, it is possible toreduce the load on the hinge portion in the air bag door portion. Stillfurther, since the air bag door portion can be constituted of a hardmaterial having a high rigidity, it is possible to prevent anoil-can-like-feeling and deformation.

Further, in a tenth aspect the present invention, in the first aspect,the air bag door portion and the main body portion are integrally formedof the same hard resin material or separately formed, and a surface ofthese base materials are covered with a skin with a common or separatedtear portion with insert molding or attachment molding.

Accordingly, the impact load from the bag body of the air bag isconcentrated at the center portion of the tear portion when the bag bodyof the air bag expands, so that the base member and the skin of the airbag door portion is smoothly broken. As a result, since breakage can beeasily performed even when the thickness of the tear portion in the basemember of the air bag door portion is made large, it is possible toreconcile expansion performance and restriction of reduction in thequality of the outer appearance (weld shrinkage and an swelling-shapedunevenness). Further, since it is possible to construct with the hardresin material having a high rigidity, it is possible to prevent anoil-can-like-feeling and deformation. Still further, in a case whereinthe air bag door portion and the main body portion are integrally formedof the same hard resin material, a complex mold structure is notrequired in comparison with a dual-injection molding, and a posttreatment of the base member is not required.

Still further, in an eleventh aspect of the present invention, in thefirst aspect, the air bag door portion and the main body portion areintegrally formed of the same hard resin material or separately formed,and a foam layer and a skin with a tear portion commonly formed orseparately formed are integrally formed on a surface of the base membersthereof.

Accordingly, the impact load from the bag body of the air bag isconcentrated at the center portion of the tear portion when the bag bodyof the air bag expands, so that the base member of the air bag doorportion, the foamed layer and the skin are smoothly broken. As a result,since it is possible to easily cause breakage even if the thickness ofthe tear portion in the base member of the air bag door portion is madelarge, it is possible to reconcile expansion performance and preventionof underfill during molding. Further, since it is possible to constructwith the hard resin material having a high rigidity, there is noswelling feeling which easily generates when estimating heat resistanceor the like.

Furthermore, in a twelfth aspect of the present invention, in the thirdaspect, the main body portion and the air bag door portion of the trimmember for the automotive vehicle integrally formed or separately formedare formed of the same resin in accordance with an injection molding.

Accordingly, by setting the resin fluidizing boundary at a core backarea, which is for forming a tear portion during expansion of the airbag door portion, it is possible to lower the break force in the breakforce to a desired value, due to strength reduction which depends on theresin fluidizing boundary. Further, since it is not necessary to makethe resin thickness of the break portion significantly thin, the line inthe break portion can be made in a state of being fully invisible fromthe side of the outer appearance, the quality of the outer appearancecan be prevented from being lowered, heat resistance and agingperformance is improved, and support and surface rigidity of a whole ofthe air bag door portion can be also improved. Still further, in a casewherein the air bag door portion and the main body portion areintegrally formed of the same resin, it is not necessary to paint thetrim member for the automotive vehicle while separating into two kindsof materials, so that low cost can be achieved.

Moreover, in a thirteenth aspect of the present invention, in the thirdaspect, a main body portion and the air bag door portion of the trimmember for the automotive vehicle has an air bag door portion integrallyformed using different resins in accordance with dual-injection molding.

Accordingly, even in the trim member for the automotive vehicle havingthe air bag door portion integrally formed by the dual-injectionmolding, by setting the resin fluidizing boundary at the core back areawhich is for forming the break portion when the air bag door portion isexpanded the break force in the break portion can be lowered to adesired value, due to strength reduction which depends on the resinfluidizing boundary. Further, since it is not necessary to make theresin thickness of the break portion significantly thin, the line in thebreak portion can be made in a state of being fully invisible from theside of the outer appearance, the quality of the outer appearance can beprevented from being lowered, heat resistance and aging performance isimproved, and support and surface rigidity of a whole of the air bagdoor portion can be also improved.

Moreover, in a fourteenth aspect of the present invention, in the thirdaspect, a main body portion of a base member and the air bag doorportion of the trim member for the automotive vehicle, which areintegrally formed or separately formed, are formed using the same resinin accordance with injection molding, the base member having an air bagdoor portion covered by a skin having a tear portion or lacking a tearportion.

Accordingly, even in the trim member for the automotive vehicle having aso-called skin insert and a skin attachment type air bag door portionwherein the base member is covered by the skin having the tear portionor lacking the tear portion, by setting the resin fluidizing boundary atthe core back area which is for forming the break portion when the airbag door portion is expanded the break force in the break portion can belowered to a desired value, due to a strength reduction which depends onthe resin fluidizing boundary. Further, since it is not necessary tomake the resin thickness of the break portion significantly thin, thequality of the outer appearance transferred to the skin can be preventedfrom being lowered, heat resistance and aging performance is improved,and support and surface rigidity of a whole of the air bag door portioncan be also improved.

Further, in a fifteenth aspect of the present invention, in the thirdaspect, a main body portion of a base member and the air bag doorportion in the trim member for the automotive vehicle, which areintegrally formed or separately formed are formed using the same resinin accordance with injection molding, the base member being covered by askin having a tear portion, and a foam layer being formed between theskin and the base member.

Accordingly, even in the trim member for the automotive vehicle having aso-called integrally foamed type air bag door portion in which the basemember is covered by the skin having a tear portion and the foamed layeris formed between the skin and the base member, by setting the resinfluidizing boundary at the core back area which is for forming the breakportion when the air bag door portion is expanded the break force in thebreak portion can be lowered to a desired value, due to strengthreduction which depends on the resin fluidizing boundary. Further, sinceit is not necessary to make the resin thickness of the break portionsignificantly thin, underfill during formation can be prevented, heatresistance and aging performance is improved, and support and surfacerigidity of a whole of the air bag door portion can be also improved.

Further, in a sixteenth aspect of the present invention, in the thirdaspect, a cavity is separated in the tear portion by bringing a slidecore having a distal end formed in a substantially triangular shape intocontact with or in the proximity of a fixed mold, and in this state aresin is injected into each of the separated cavities, moving the slidecore slightly backward at about the time filling is completed.

Accordingly, the resin fluidizing boundary can be set at the breakportion when the air bag door portion is broken by a simple method ofseparating the cavity of the air bag door portion, injecting the resininto each of the cavities in this state and slightly moving backward theslide core under condition at about the time filling of the resin iscompleted, by means of the slide core having the distal end formed in asubstantially triangular shape. As a result, since current moldingequipment can be used, it is possible to manufacture at low cost.Further, since the method is simple, high reliability can be achieved infunctional quality and high productivity can also be achieved.

Further, in a seventeenth aspect of the present invention, in thesixteenth aspect, wherein the break strength of the tear portion can becontrolled with a combination of a keep pressure and a core back timingat about the time filling is completed and the thickness near the tearportion.

Accordingly, it is possible to easily and accurately control the breakstrength of the break portion to a desired value with a combination ofthe keep pressure before and after filling is completed, the core backtiming and the thickness near the break portion.

Further, in an eighteenth aspect of the present invention, in theseventeenth aspect, the core back timing is set to after the filling iscompleted.

When the core back timing is too soon with respect to completion offilling, the resin filled first is fluidized within a space at the sidewherein filling is not completed, so that the resin fluidizing boundaryis shifted from the breakage expected portion which depends on the slidecore. However, in contrast, in accordance with the present invention,since the core back timing is set to after filling is completed, inaddition to the contents stated in claim 6, it is possible to preventthe resin fluidizing boundary and the breakage expected portion fromshifting the positions thereof.

Further, in a nineteenth aspect of the present invention, in theeighteenth aspect, the keep pressure after the filling is completed isdecreased, separating into several stages, and the core back timing isset to after a second stage of the keep pressure.

Accordingly, since the first stage of the keep pressure can be reliablyperformed by setting the core back timing to after the second stage ofthe keep pressure, the weight, size and shape of the formed product canbe stabilized, so that generation of deficiencies in the product can bereduced.

Further, a twentieth aspect of the present invention comprises: a tearportion formed in the air bag door portion; and push-up means forpushing up a portion at both sides or one side of the air bag doorportion having therebetween a center portion of the tear portion when abag body of the air bag is expanded, wherein a resin fluidizing boundaryis set at a core back area for forming the tear portion, and a line ofthe tear portion can not be seen from a side of an outer appearance.

Accordingly, the impact load from the bag body of the air bag isconcentrated at the center portion of the tear portion when the bag bodyof the air bag is expanded, since the push-up means is provided.Further, since the resin fluidizing boundary is set at the core backarea which is for forming the break portion when the air bag doorportion is expanded, it is possible to decrease the break force of thebreak portion to a desired value, due to strength reduction whichdepends on the resin fluidizing boundary. As a result, it is possible todevise to reconcile expansion performance and the quality of the outerappearance (making invisible).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged cross-sectional view along a line 1—1 in FIG. 3.

FIG. 2 is an enlarged side sectional view which shows main portions ofan interior member for an automotive vehicle having an air bag doorportion in accordance with a first embodiment of the present invention.

FIG. 3 is a perspective view as seen from behind and at an angle withrespect to the automotive vehicle which shows an instrument panel as thetrim member for the automotive vehicle having the air bag door portionin accordance with the first embodiment of the present invention.

FIG. 4 is an enlarged plan view which shows a portion of the trim memberfor the automotive vehicle having the air bag door portion in accordancewith the first embodiment of the present invention.

FIG. 5 is an enlarged plan view which shows a portion of an interiormember for an automotive vehicle having an air bag door portion inaccordance with a modified embodiment of the first embodiment of thepresent invention.

FIG. 6A is a schematic plan view which shows a positional relationbetween the portion and the tear portion in the trim member for theautomotive vehicle having the air bag door portion in accordance withthe modified embodiment of the first embodiment of the presentinvention.

FIG. 6B is a schematic plan view which shows a positional relationbetween the portion and the tear portion in the trim member for theautomotive vehicle having the air bag door portion in accordance withthe modified embodiment of the first embodiment of the presentinvention.

FIG. 6C is a schematic plan view which shows a positional relationbetween the portion and the tear portion in the trim member for theautomotive vehicle having the air bag door portion in accordance withthe modified embodiment of the first embodiment of the presentinvention.

FIG. 6D is a schematic plan view which shows a positional relationbetween the portion and the tear portion in the trim member for theautomotive vehicle having the air bag door portion in accordance withthe modified embodiment of the first embodiment of the presentinvention.

FIG. 6E is a schematic plan view which shows a positional relationbetween the portion and the tear portion in the trim member for theautomotive vehicle having the air bag door portion in accordance withthe modified embodiment of the first embodiment of the presentinvention.

FIG. 7 is a side sectional view corresponding to FIG. 1, showing aninterior member for an automotive vehicle having an air bag door portionin accordance with a second embodiment of the present invention.

FIG. 8 is a view for explaining an operation, which shows the trimmember for the automotive vehicle having the air bag door portion inaccordance with the second embodiment of the present invention.

FIG. 9 is a plan view which shows a metal plate of the trim member forthe automotive vehicle having the air bag door portion in accordancewith the second embodiment of the present invention.

FIG. 10 is a side sectional view corresponding to FIG. 8, showing aninterior member for an automotive vehicle having an air bag door portionin accordance with a modified embodiment of the second embodiment of thepresent invention.

FIG. 11 is a plan view which shows a metal plate of the trim member forthe automotive vehicle having the air bag door portion in accordancewith the modified embodiment of the second embodiment of the presentinvention.

FIG. 12 is a side sectional view corresponding to FIG. 1, which shows aninterior member for an automotive vehicle having an air bag door portionin accordance with a third embodiment of the present invention.

FIG. 13 is a view for explaining an operation, which shows the trimmember for the automotive vehicle having the air bag door portion inaccordance with the third embodiment of the present invention.

FIG. 14 is a side sectional view corresponding to FIG. 1, showing aninterior member for an automotive vehicle having the air bag doorportion in accordance with a modified embodiment of the third embodimentof the present invention.

FIG. 15 is a side sectional view corresponding to FIG. 1, showing aninterior member for an automotive vehicle having an air bag door portionin accordance with a fourth embodiment of the present invention.

FIG. 16 is a side sectional view corresponding to FIG. 1, showing aninterior member for an automotive vehicle having an air bag door portionin accordance with a fifth embodiment of the present invention.

FIG. 17A is a cross-sectional view which shows a skin formed by a skininsert molding in the interior member for the automotive vehicle havingthe air bag door portion in accordance with the present invention.

FIG. 17B is a cross-sectional view which shows the skin formed by theskin insert molding in the interior member for the automotive vehiclehaving the air bag door portion in accordance with the presentinvention.

FIG. 17C is a cross-sectional view which shows the skin formed by theskin insert molding in the interior member for the automotive vehiclehaving the air bag door portion in accordance with the presentinvention.

FIG. 18A is a cross-sectional view which shows a skin formed by anattachment molding in the interior member for the automotive vehiclehaving the air bag door portion in accordance with the presentinvention.

FIG. 18B is a cross-sectional view which shows a skin formed by anattachment molding in the interior member for the automotive vehiclehaving the air bag door portion in accordance with the presentinvention.

FIG. 19 is a side sectional view corresponding to FIG. 1, showing aninterior member for an automotive vehicle having an air bag door portionin accordance with a sixth embodiment of the present invention.

FIG. 20 is a side sectional view corresponding to FIG. 1, showing aninterior member for an automotive vehicle having an air bag door portionin accordance with a seventh embodiment of the present invention.

FIG. 21 is a view for explaining an operation, which shows the trimmember for the automotive vehicle having the air bag door portion inaccordance with the seventh embodiment of the present invention.

FIG. 22 is an enlarged plan view which shows a reverse face of the airbag door portion in the trim member for the automotive vehicle havingthe air bag door portion in accordance with the seventh embodiment ofthe present invention.

FIG. 23A is a schematic plan view which shows a positional relationbetween a groove and a tear portion in an interior member for anautomotive vehicle having an air bag door portion in accordance with amodified embodiment of the seventh embodiment of the present invention.

FIG. 23B is a schematic plan view which shows a positional relationbetween the groove and the tear portion in the interior member for theautomotive vehicle having the air bag door portion in accordance withthe modified embodiment of the seventh embodiment of the presentinvention.

FIG. 23C is a schematic plan view which shows a positional relationbetween the groove and the tear portion in the interior member for theautomotive vehicle having the air bag door portion in accordance withthe modified embodiment of the seventh embodiment of the presentinvention.

FIG. 23D is a schematic plan view which shows a positional relationbetween the groove and the tear portion in the interior member for theautomotive vehicle having the air bag door portion in accordance withthe modified embodiment of the seventh embodiment of the presentinvention.

FIG. 23E is a schematic plan view which shows a positional relationbetween the groove and the tear portion in the interior member for theautomotive vehicle having the air bag door portion in accordance withthe modified embodiment of the seventh embodiment of the presentinvention.

FIG. 23F is a schematic plan view which shows a positional relationbetween the groove and the tear portion in the interior member for theautomotive vehicle having the air bag door portion in accordance withthe modified embodiment of the seventh embodiment of the presentinvention.

FIG. 24 is an enlarged cross-sectional view along a line 1—1 in FIG. 25.

FIG. 25 is a perspective view which shows an interior member for anautomotive vehicle integrally having an air bag door portion inaccordance with an eighth embodiment of the present invention.

FIG. 26 is a schematic cross-sectional view which shows a process in amethod of forming the trim member for the automotive vehicle integrallyhaving the air bag door portion in accordance with the eighth embodimentof the present invention.

FIG. 27 is a schematic cross-sectional view which shows a process in amethod of forming the trim member for the automotive vehicle integrallyhaving the air bag door portion in accordance with the seventhembodiment of the present invention.

FIG. 28 is a timing chart which shows a method of forming the trimmember for the automotive vehicle integrally having the air bag doorportion in accordance with the eighth embodiment of the presentinvention.

FIG. 29A is a schematic plan view which shows an area of a slide corewith respect to an H-shaped thin portion of the trim member for theautomotive vehicle integrally having the air bag door portion inaccordance with the eighth embodiment of the present invention.

FIG. 29B is a schematic plan view which shows an area of the slide corewith respect to the H-shaped thin portion of the trim member for theautomotive vehicle integrally having the air bag door portion inaccordance with the eighth embodiment of the present invention.

FIG. 29C is a schematic plan view which shows an area of the slide corewith respect to the H-shaped thin portion of the trim member for theautomotive vehicle integrally having the air bag door portion inaccordance with the eighth embodiment of the present invention.

FIG. 29D is a schematic plan view which shows an area of the slide corewith respect to the H-shaped thin portion of the trim member for theautomotive vehicle integrally having the air bag door portion inaccordance with the eighth embodiment of the present invention.

FIG. 29E is a schematic plan view which shows an area of the slide corewith respect to the H-shaped thin portion of the trim member for theautomotive vehicle integrally having the air bag door portion inaccordance with the eighth embodiment of the present invention.

FIG. 29F is a schematic plan view which shows an area of the slide corewith respect to the H-shaped thin portion of the trim member for theautomotive vehicle integrally having the air bag door portion inaccordance with the eighth embodiment of the present invention.

FIG. 29G is a schematic plan view which shows an area of the slide corewith respect to the H-shaped thin portion of the trim member for theautomotive vehicle integrally having the air bag door portion inaccordance with the eighth embodiment of the present invention.

FIG. 29H is a schematic plan view which shows an area of a slide corewith respect to a C-shaped thin portion of a trim member for anautomotive vehicle integrally having an air bag door portion inaccordance with an applied embodiment of the present invention.

FIG. 29I is a schematic plan view which shows an area of the slide corewith respect to the C-shaped thin portion of the trim member for theautomotive vehicle integrally having the air bag door portion inaccordance with the applied embodiment of the present invention.

FIG. 29J is a schematic plan view which shows an area of the slide corewith respect to the C-shaped thin portion of the trim member for theautomotive vehicle integrally having the air bag door portion inaccordance with the applied embodiment of the present invention.

FIG. 29K is a schematic plan view which shows an area of the slide corewith respect to the C-shaped thin portion of the trim member for theautomotive vehicle integrally having the air bag door portion inaccordance with the applied embodiment of the present invention.

FIG. 30A is a schematic cross-sectional view which shows across-sectional shape of a thin portion of a trim member for anautomotive vehicle integrally having an air bag door portion inaccordance with an applied embodiment of the eighth embodiment of thepresent invention.

FIG. 30B is a schematic cross-sectional view which shows across-sectional shape of the thin portion of the trim member for theautomotive vehicle integrally having the air bag door portion inaccordance with the applied embodiment of the eighth embodiment of thepresent invention.

FIG. 31 is a schematic cross-sectional view which shows a step in aforming process for the trim member for the automotive vehicleintegrally having the air bag door portion in accordance with theapplied embodiment of the eighth embodiment of the present invention.

FIG. 32A is a side sectional view which shows an air bag door portion ofan interior member for an automotive vehicle integrally having an airbag door portion in accordance with an applied embodiment of anembodiment of the present invention.

FIG. 32B is a perspective view which shows the air bag door portion ofthe trim member for the automotive vehicle integrally having the air bagdoor portion in accordance with the applied embodiment of the embodimentof the present invention.

FIG. 33 is a graph which shows a variation in the keep pressure duringformation of the trim member for the automotive vehicle integrallyhaving the air bag door portion in accordance with the eighth embodimentof the present invention.

FIG. 34 is a cross-sectional view corresponding to FIG. 24 which showsthe interior member for the automotive vehicle integrally having the airbag door portion in accordance with the applied embodiment of the eighthembodiment of the present invention.

FIG. 35 is a cross-sectional view corresponding to FIG. 24 which showsan interior member for an automotive vehicle integrally having an airbag door portion in accordance with another applied embodiment of theeighth embodiment of the present invention.

FIG. 36 is a cross-sectional view which explains two factors influencingthe weld strength between a first resin and a second resin.

FIG. 37A is a graph which shows a relation between the keep pressure andthe tear portion break force.

FIG. 37B is a graph which shows a relation between the core back timingand the tear portion break force.

FIG. 37C is a graph which shows a relation between the thickness in aperiphery of the tear portion and the tear portion break force.

FIG. 38 is a cross-sectional view corresponding to FIG. 24 showing aninterior member for an automotive vehicle integrally having an air bagdoor portion in accordance with another embodiment of the presentinvention.

FIG. 39 is a cross-sectional view corresponding to FIG. 24 showing aninterior member for an automotive vehicle integrally having an air bagdoor portion in accordance with another embodiment of the presentinvention.

FIG. 40 is a cross-sectional view corresponding to FIG. 24 showing aninterior member for an automotive vehicle integrally having an air bagdoor portion in accordance with another embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of a interior member for an automotive vehicle havingan air bag door portion in accordance with the present invention will bedescribed below with reference to FIGS. 1 to 4.

Here, in the drawings, an arrow FR indicates a forward direction of anautomotive vehicle, and an arrow UP indicates an upward direction an theautomotive vehicle.

As shown in FIG. 1, in an instrument panel 10, which is a trim memberfor an automotive vehicle provided within a vehicle cabin of theautomotive vehicle, an air bag apparatus 12 is arranged inside anassistant driver's seat. An air bag case 14 for this air bag apparatus12 is fixed to an instrument panel reinforcement (not shown), and aninflator 16 and a air bag body 18 in a folded state is contained withinthe air bag case 14.

Further, a portion in a position substantially opposite to that of theair bag case 14 of the instrument panel 10 serves as an air bag doorportion 20, and a portion other than the air bag door portion 20 of theinstrument panel 10 serves as a main body portion 22. The air bag doorportion 20 and the main body portion 22 are constituted of TSOP, whichis a hard resin [obtained by making an elastomer (a rubber) and a PP (apolypropylene) Broy (a technique for making a high polymermulticomponent material of which can be expected a multiplier effect)and adding a talc so as to make it complex and strong, a PP that has alow specific gravity, impact resistance, rigidity and excellentfluidity, is suitable for a thin product, and has, for example, a rateof a flexural modulus of elasticity of 1500 to 3000 Mpa], a PP resin,PC/ABS resin, a denatured PPO resin, a PC/PBT resin, an ABS resin, a PCresin, an ASG resin, a TPO resin, a TPE resin, a TPU resin, aPC/denatured PS resin or the like.

The air bag apparatus 12 is structured such that when a suddendeceleration of the automotive vehicle is detected by a mechanical orelectrical acceleration sensor (not shown), the inflator 16 within theair bag case 14 is operates so as to expand the air bag body 18,contained within the air bag case 14 in a folded state, toward the airbag door portion 20 of the instrument panel 10. The air bag body 18 isstructured such as to press the air bag door portion 20 in theinstrument panel 10 so as to break and open the air bag door portion 20,thereby expanding within the vehicle cabin. In this case, since aconventionally known popular structure can be applied to the air bagapparatus 12, detailed descriptions of the air bag apparatus 12 will beomitted in this embodiment.

As shown in FIG. 3, a tear portion 24 which was made thin is formed in acenter portion in a longitudinal direction and both end portions in alateral direction of the air bag door portion 20 so as to be formed inan H shape, and it is structured such that the air bag door portion 20is opened toward both directions in a longitudinal direction when thebag body of the air bag is expanded, so that the bag body of the air bagis expanded within the vehicle cabin.

As shown in FIG. 2, a cross section of the tear portion 24 of the airbag door portion 20 is formed in a V shape. Further, in the air bag doorportion 20, protrusions 28 and 30 serving as push-up means is providedat positions at two sides in a longitudinal direction of the automotivevehicle having therebetween a center portion 24A of the tear portion 24so as to protrude downward, and the protrusions 28 and 30 are integrallyformed with the air bag door portion 20. Accordingly, it is structuredsuch that when the bag body of the air bag is expanded, the expandingbag body of the air bag abuts lower surfaces 28A and 30A of theprotrusions 28 and 30, thereby pressing the protrusions 28 and 30 upward(in a direction of an arrow A in FIG. 2).

As shown in FIG. 4, the protrusions 28 and 30 are formed in a latticeform by a narrow rib 32 extending in a longitudinal direction of theautomotive vehicle and a narrow rib 34 extending in a lateral directionof the automotive vehicle. A width T1 of these ribs 32 and 34 is set tobe equal to or less than half a thickness T of the air bag door portion20 shown in FIG. 2, so that shrinkage is prevented.

Further, a width W1 and a length L1 of the protrusions 28 and 30 arerespectively set to be about 5 to 20% a total width W and a total lengthL of a front door portion 20A and a rear door portion 20B of the air bagdoor portion 20 shown in FIG. 3. Accordingly, the air bag door portion20 is structured such that deflections in the lateral direction and thelongitudinal direction are not significantly hampered by the protrusions28 and 30, and the air bag door portion 20 is deflected in the lateraldirection and the longitudinal direction when the bag body of the airbag is expanded, thereby being securely broken from the center portion24A of the tear portion 24.

In this case, as shown in FIG. 1, a hinge portion 26 which has been madethin is formed at both end portions in the longitudinal direction of theair bag door portion 20. Accordingly, the air bag door portion 20 isstructured such that when it is pressed by the expanding air bag body 18when the air bag is expanded, it is opened and broken along the tearportion 24, so that the opened and broken front door portion 20A andrear door portion 20B rotate around the hinge portions 26 and an openingfor expanding the air bag body 18 within the vehicle cabin is formed.

In this case, as shown in FIGS. 2 and 4, each of corner portions 28B,30B, 28C, 30C, 28D, 30D, 29E and 30E of the protrusions 28 and 30abutting the air bag body 18 when the bag body of the air bag isexpanded, is beveled, thereby protecting the air bag body 18.

Next, an operation of the first embodiment in accordance with thepresent invention will be described below.

In this first embodiment, when the bag body of the air bag is expanded,the expanding air bag body abuts the lower surfaces 28A and 30A of theprotrusions 28 and 30, thereby pressing the protrusions 28 and 30 upward(the direction of the arrow A in FIG. 2). Accordingly, an impact loadacts on the protrusions 28 and 30 from the air bag body 18 momentarily,and breakage is smoothly performed from the center portion 24A of thetear portion 24. As a result, since the tear portion 24 can be easilybroken even when the thickness thereof is large, it is possible todevise to reconcile expansion performance and the quality of the outerappearance (making invisible).

Further, a load on the hinge portions 26 can be lightened. Stillfurther, since the air bag door portion 20 can be constituted of a hardmaterial having a high rigidity, an oil-can-like-feeling and deformationcan be prevented. Furthermore, it is possible to devise to reconcile thequality of the outer appearance and expansion performance through asimple structure in which the protrusions 28 and 30 are merely providedin the air bag door portion 20.

Still further, since the protrusions 28 and 30 are formed by the ribs 32and 34 integrally formed with the air bag door portion 20, theprotrusions 28 and 30 can be formed without mounting a separate part,and since the width (T1) between the ribs 32 and 34 is narrower than thethickness (T) of the normal portion of the air bag door portion 20(T1≦T/2), generation of shrinkage on the surface of the air bag doorportion 20 caused by the ribs 32 and 34 after injection molding can berestricted, so that the quality of the outer appearance is notdeteriorated.

In this case, in accordance with the first embodiment, as shown in FIG.4, the protrusions 28 and 30 are formed in a lattice form by the narrowrib 32 extending in the longitudinal direction and the narrow rib 34extending in the lateral direction; however, the shape of theprotrusions 28 and 30 is not limited to this, for example, another shapesuch as an E shape or the like may be employed as shown in FIG. 5.

Further, in accordance with the first embodiment, as shown in FIG. 3,the tear portion 24 is formed in an H shape in a plan view, however, theshape of the tear portion 24 is not limited to this, for example, alinear shape as shown in FIG. 6A, a double-Y shape as shown in FIG. 6B,an X shape as shown in FIG. 6C and the like may be employed. Stillfurther, as shown in FIG. 6D, in a case wherein the tear portion 24 isformed in an X shape, the portions 29 and 31 may be formed by closing inthe tear portion 24 in the lateral direction as well. Furthermore, asshown in FIG. 6E, in a case wherein the tear portion 24 is formed in a Cshape, it is possible to form only the portion 28, at one side of thetear portion 24.

Next, a second embodiment of a interior member for an automotive vehiclehaving an air bag door portion will be described below with reference toFIGS. 7 to 9.

In this case, the same reference numerals are attached to the sameelements as those in the first embodiment, and an explanation thereofwill be omitted.

As shown in FIG. 7, in this second embodiment, metal plates 36 and 38made of a metal, for example, aluminum, iron, stainless steel or thelike, are respectively disposed below the front door portion 20A and therear door portion 20B of the air bag door portion 20. A front endportion 36A of the metal plate 36 is fastened to both the air bag case14 and the main body portion 22 of the instrument panel 10 by a bolt 40passing through a mounting hole 39 punched into the metal plate 36. Arear end portion 38A of the metal plate 38 is fastened to both the airbag case 14 and the main body portion 22 of the instrument panel 10 by abolt 42 passing through a mounting hole 41 punched into the metal plate38. Further, a rear distal end portion 36B of the metal plate 36 and afront distal end portion 38B of the metal plate 38 are respectively bentdownward to have a rectangular cross section so as to be portions 44 and46 as push-up means, and these portions 44 and 46 are respectivelystructured such as to abut portions at both sides in the lateraldirection of the air bag door portion 20 having therebetween the centerportion 24A of the tear portion 24 when the bag body of the air bag isexpanded.

As shown in FIG. 9, the metal plate 36 is formed in a trapezoidal shapein which a rear portion is narrow in a plan view, and the metal plate 38is formed in a trapezoidal shape in which a front portion is narrow.Further, a width W2 and a length L2 of the portions 44 and 46 arerespectively set to be about 5 to 20% the total width W and the totallength L of the front door portion 20A and the rear door portion 20B inthe air bag door portion 20 shown in FIG. 3. Accordingly, the air bagdoor portion 20 is structured such that deflections in the lateraldirection and the longitudinal direction are not significantly hamperedby the protrusions 28 and 30, and the air bag door portion 20 isdeflected in the lateral direction and the longitudinal direction whenthe bag body of the air bag is expanded, thereby being securely brokenfrom the center portion 24A of the tear portion 24.

Next, an operation of the second embodiment in accordance with thepresent invention will be described below.

In this second embodiment, during expansion of the air bag body 18, theexpanding bag body of the air bag abuts the lower surfaces 44A and 46Aof the portions 44 and 46 in the metal plates 36 and 38, as shown inFIG. 8, thereby pressing the portions 44 and 46 upward (a direction ofan arrow A in FIG. 8). Accordingly, an impact load from the air bag body18 momentarily acts on both sides in the lateral direction of the centerportion 24A of the tear portion 24 in the air bag door portion 20 viathe portions 44 and 46. Accordingly, the air bag door portion 20 issmoothly broken from the center portion 24A of the tear portion 24. As aresult, since the tear portion 24 can be easily broken even when thethickness thereof is large, it is possible to devise to reconcile theexpansion performance and the quality of the outer appearance (makinginvisible).

Further, in the second embodiment, the portions 44 and 46 are formed atthe lower side of the metal plates 36 and 38, that is, at the side ofthe air bag body 18; however, alternatively, as shown in FIG. 10, theportions 44 and 46 may be formed at the side of the upper surface of themetal plates 36 and 38, that is, at the side of the air bag door portion20. In this case, by providing the portions 44 and 46 at the uppersurface of the distal ends 36B and 38B of the metal plates 36 and 38, asshown in FIG. 10, even when the upper surface 18A of the air bag body 18becomes an uneven shape during an initial period of expansion, the airbag body 18 reliably abuts each of the lower surfaces of the flat metalplates 36 and 38 so as to push up the portions 44 and 46 in thedirection of the arrow A, so that it is possible to securely break fromthe center portion 24A of the tear portion 24. Further, as shown in FIG.11, in a case of forming the portions 44 and 46 at the side of the uppersurface of the metal plates 36 and 38, that is, at the side of the airbag door portion 20, even when the shape in a plan view of the metalplates 36 and 38 is rectangular, the portions 44 and 46 can reliablyabut the portions at both sides in the longitudinal direction of theautomotive vehicle having therebetween the center portion of the tearportion in the air bag door portion. Further, in accordance with thesecond embodiment, hinge portions are not particularly formed in themetal plates 36 and 38; however, at positions substantially opposite tothat of the hinge portions 26 of the air bag door portion 20, the metalplates 36 and 38 may be bent upward or downward in U-shaped forms,thereby having them serve as hinge portions.

Next, a third embodiment of a interior member for an automotive vehiclehaving an air bag door portion will be described below with reference toFIGS. 12 and 13.

In this case, the same reference numerals are attached to the sameelements as those in the first embodiment, and an explanation thereofwill be omitted.

As shown in FIG. 12, in this third embodiment, metal plates 48 and 50made of a metal, for example, aluminum, iron, stainless steel or thelike are respectively disposed below the front door portion 20A and therear door portion 20B of the air bag door portion 20. A front endportion 48A of the metal plate 48 is fixed to the air bag case 14 by abolt 51 and a nut 52 and a rear end portion 50A of the metal plate 50 isfixed to the air bag case 14 by a bolt 53 and a nut 54. Further, hingeportions 48B and 50B of the metal plates 48 and 50 are made thin. Thehinge portions 48B and 50B are off set below the hinge portions 26 ofthe air bag door portion 20 (with off-set amounts H1 and H2) and off setwith respect to the center portion 24A of the tear portion 24 (withoff-sets amounts K1 and K2). Further, portions between the hingeportions 48B and 50B and the front end portion 48A and the rear endportion 50A respectively which serve as a mounting portion thereof, andportions between the hinge portions 48B and 50B and the front endportions 48C and 50C respectively have a rigidity higher than that ofthe hinge portions 48B and 50B. Namely, only the hinge portions 48B and50B are made thin and have low rigidity.

Next, an operation of the third embodiment will be described below.

In this third embodiment, the air bag body 18 expand when the bag bodyof the air bag is expanded abuts the lower surfaces of the metal plates48 and 50, as shown in FIG. 13, thereby pressing the front end portions48C and 50C of the metal plates 48 and 50 upward (the direction of thearrow A in FIG. 13). Accordingly, since an impact load from the air bagbody 18 momentarily acts on both sides in the lateral direction of thecenter portion 24A of the tear portion 24 in the air bag door portion 20via the front end portions 48C and 50C of the metal plates 48 and 50having a high rigidity, the air bag door portion 20 is smoothly brokenfrom the center portion 24A of the tear portion 24. As a result, sincethe tear portion 24 can be easily broken even when the thickness thereofis large, it is possible to devise to reconcile the expansionperformance and the quality of the outer appearance (making invisible).

Further, since the hinge portions 48B and 50B of the metal plates 48 and50 are off set with respect to the center portion 24A of the tearportion 24 more than the hinge portion 26 of the air bag door portion20, and the portion between the hinge portions 48B and 50B respectivelyof the metal plates 48 and 50 and the front end portions 48A and rearend portion 50A serving as the mounting portions are made highly rigid,it is possible to prevent the air bag body 18 from directly abutting thehinge portions 26 of the air bag door portion 20 due to the portionsbetween the hinge portions 48B and 50B respectively of the metal plates48 and 50 and the front end portion 48A and the rear end portion 50Arespectively, when the bag body of the air bag is expanded, so that itis possible to prevent the hinge portions 26 of the air bag door portion20 from breaking such as cracking due to the air bag body 18.

Further, in the third embodiment, the hinge portions 48B and 50B of themetal plates 48 and 50 are made thin; however, in place of this, asshown in FIG. 14, the hinge portions 48B and 50B may be made as anotherstructure wherein the metal plates 48 and 50 are bent upward in aU-shaped form, or the like.

Next, a fourth embodiment of a interior member for an automotive vehiclehaving an air bag door portion will be described below with reference toFIG. 15.

In this case, the same reference numerals are attached to the sameelements as those in the third embodiment, and an explanation thereofwill be omitted.

As shown in FIG. 15, in this fourth embodiment, door hinge portionprotecting plates 56 and 58 having a high break force and made of ametal, for example, aluminum, iron, stainless steel or the like, arerespectively disposed below the front door portion 20A and the rear doorportion 20B of the air bag door portion 20. A front portion 56A of thedoor hinge portion protecting plate 56 is fixed to the air bag case 14by the bolt 51 and the nut 52, and a rear portion 58A of the door hingeportion protecting plate 58 is fixed to the air bag case 14 by the bolt53 and the nut 54. Further, a rear portion 56B of the door hinge portionprotecting plate 56 and a front portion 58B of the door hinge portionprotecting plate 58 respectively protrude toward the center portion 24Aof the tear portion 24 rather than toward the hinge portions 26 of theair bag door portion 20, and further are extended to a position near thereverse face of the air bag door portion 20. In this case, each of theextending portions of the rear portion 56B of the door hinge portionprotecting plate 56 and the front portion 58B of the door hinge portionprotecting portion 58 is structured such as to be plastically deformedto a certain degree due to by the impact load from the air bag body 18.

Next, an operation of the fourth embodiment will be described below.

In this fourth embodiment, since the rear portion 56B and the frontportion 58B of the door hinge portion protecting plates 56 and 58respectively protrude toward the center portion 24A of the tear portion24 rather than toward the hinge portions 26 of the air bag door portion20, and further, are extended to a position near the reverse face of theair bag door portion 20, it is possible to prevent the air bag body 18from directly abutting the hinge portions 26 of the air bag door portion20 when the bag body of the air bag is expanded, so that it is possibleto prevent the hinge portions 26 from breaking due to the air bag body18. Further, since the hinge portions 26 of the air bag door portion 20can be protected, it is easy to break from the center portion 24A of thetear portion 14, which has a relatively low strength.

Next, a fifth embodiment of a interior member for an automotive vehiclehaving an air bag door portion will be described below with reference toFIG. 16.

In this case, the same reference numerals are attached to the sameelements as those in the first embodiment, and an explanation thereofwill be omitted.

As shown in FIG. 16, in the fifth embodiment, the air bag door portion20, as the base member of the air bag door portion, and the main bodyportion 22, as the base member of the main body portion, are integrallyformed of the same hard resin material, and a skin 62, for example, madeof PVC, TPO, fabric or the like, is disposed on an obverse face (anouter appearance) of the integrally formed base member 60 in accordancewith an insert molding or an attachment molding. Further, a tear portion64 which has been made thin, for example, is formed on the reverse face(the base material) side of the skin 62 or on the obverse face sidethereof along the tear portion 24 of the base member, and the skin 62covers the obverse face (the outer appearance) of the base member 60.

Next, an operation of the fifth embodiment will be described below.

In this fifth embodiment, when the bag body of the air bag is expandedthe air bag body 18 abuts the lower surfaces 28A and 30A of theprotrusions 28 and 30, thereby pressing the protrusions 28 and 30upward. Accordingly, an impact load acts on the protrusions 28 and 30from the air bag body 18, breakage is smoothly performed from the centerportion 24A of the tear portion 24, and the skin 62 smoothly breaks fromthe tear portion 60 as well. As a result, since the tear portion 24 canbe easily broken even when the thickness thereof is large, it ispossible to devise to reconcile expansion performance and the quality ofthe outer appearance (making invisible).

Further, a load on the hinge portion 26 can be reduced. Still further,since the air bag door portion 20 can be constituted of a hard materialhaving a high rigidity, an oil-can-like-feeling and deformation can beprevented. Furthermore, it is possible to reconcile expansionperformance and restriction of deterioration in the quality of the outerappearance (weld shrinkage and undulation-shaped unevenness in the basenumber) transferred to the skin 62, through a simple structure in whichthe protrusions 28 and 30 are merely provided in the air bag doorportion 20. Moreover, a complex mold structure is not required incomparison with coinjection molding, and a post treatment of the tearportion 24 of the base member 60 is not required.

Further, in a case of skin insert molding, in addition to the skin 62 ofa single layer shown in FIG. 17A, the skin 62 of two layers shown inFIG. 17B and the skin 62 of three layers shown in FIG. 17C may be used.Further, in FIGS. 17A to 17C, reference numeral 63 denotes a foam layer,and reference numeral 48 denotes a barrier layer.

Further, in a case of attachment molding, in addition to the skin 62 ofa single layer shown in FIG. 18A, the skin 62 with the foam layer 63shown in FIG. 18B may be used.

Next, a sixth embodiment of a interior member for an automotive vehiclehaving an air bag door portion will be described below with reference toFIG. 19.

In this case, the same reference numerals are attached to the sameelements as those in the fifth embodiment, and an explanation thereofwill be omitted.

As shown in FIG. 19, in this sixth embodiment, a foam layer 70, forexample, constituted of an urethane foam is integrally foamed betweenthe base member 60 and the skin 62.

Next, an operation of the sixth embodiment will be described below.

In this sixth embodiment, when the bag body of the air bag is expanded,the expanding air bag body 18 abuts the lower surfaces 28A and 30A ofthe protrusions 28 and 30, thereby pressing the protrusions 28 and 30upward. Accordingly, an impact load acts on the protrusions 28 and 30from the air bag body 18, breakage is smoothly performed from the centerportion 24A of the tear portion 24, and the foam layer 70 and the skin62 also smoothly break. As a result, since the tear portion 24 can beeasily broken even when the thickness thereof is large, it is possibleto devise to reconcile expansion performance and the quality of theouter appearance (making invisible).

Further, a load on the hinge portions 26 can be reduced. Still further,since the air bag door portion 20 can be constituted of a hard materialhaving a high rigidity, an oil-can-like-feeling and deformation can beprevented. Furthermore, it is possible to reconcile expansionperformance and restriction of deterioration in the quality of the outerappearance (weld shrinkage and an undulation-shaped unevenness)transferred to the skin 62, through a simple structure in which theprotrusions 28 and 30 are merely provided in the air bag door portion20. Moreover, in comparison with the conventional integrally foamingtype, a reinforcing iron plate and a fastening part for a separate doorbase member are not required, and a fastening operation is not required.

Next, a seventh embodiment of a interior member for an automotivevehicle having an air bag door portion will be described below withreference to FIGS. 20 to 22.

In this case, the same reference numerals are attached to the sameelements as those in the first embodiment, and an explanation thereofwill be omitted.

As shown in FIG. 20, in this seventh embodiment, in contrast with thefirst embodiment, the portions are not formed in the air bag doorportion 20, and the hinge portions 26 of the air bag door portion 20correspond to thin portions having a predetermined thickness N and apredetermined longitudinal width M that is adjacent to case mountingportions 72 for mounting the air bag case 14 formed in the main bodyportion 22. Further, grooves 74 and 76 having a U-shaped cross sectionand corresponding to a bending point are formed in the middle of thelongitudinal width of the hinge portions 26.

As shown in FIG. 22, in the hinge portions 26 of the air bag doorportion 20, portions 26A which do not set the grooves 74 and 76 are setat both sides of the groove 76 in the lateral direction, and neitherends of the grooves 74 and 76 continue to the tear lines 24B and 24C inthe longitudinal direction of the tear portion 24. Further, incomparison with the groove 74 at the forward side of the automotivevehicle, the groove 76 at the rear side of the automotive vehicle islong, and the depth of the groove 76 is deeper than the depth of thegroove 74.

Further, end portions 80 of the tear lines 24B and 24C in thelongitudinal direction of the tear portion 24 are all formed in astraight line-terminating form.

Next, an operation of the seventh embodiment will be described below.

In this seventh embodiment, as shown in FIG. 21, a bending point S ofthe hinge portion of the air bag door portion 20, when the bag body ofthe air bag is expanded, is positioned at the position of the groove 74,so that it can be placed apart from the boundary P, which is a boundarywith respect to the case mounting portion 72 at which the thickness issuddenly changed. As a result, the local bending expansion ratedependent on the bending of the hinge portion 26 (the stretching rate ofa skin layer that is outside with respect to the bend) can be madesmall. Further, since the groove 74 was formed, the surface expansionlength of the bending portion can be increased, and the actual expansionrate can be made small, so that the hinge portion 26 can be effectivelyprevented from breaking due to bending when the bag body of the air bagis expanded.

Further, since the portions 26A which do not set the grooves 74 and 76are provided in the lateral direction, the hinge portions 26 can beprevented from breaking due to shearing force during an initial periodwhen the bag body of the air bag is exapnding, and the resin fluidity isprevented from being lowered, due to the reduction of the thicknessduring injection molding, which is dependent upon the grooves 74 and 76being set. Further, the door expanding angle (the door bending angle)can be adjusted by adjusting the length of the grooves 74 and 76.

Further, since the tear portion 24 of the air bag door portion 20 isformed in an H shape, and since neither ends of the grooves 74 and 76continue to the tear lines 24B and 24C in the longitudinal direction ofthe tear portion 24, a broken crack of the grooves 74 and 76 in thedirection of the tear lines 24B and 24C due to bending is prevented fromexpanding.

Further, since the end portion 80 of the tear lines 24B and 24C in thelongitudinal direction of the H-shaped tear portion 24 is formed in thestraight line-terminating form, a crack due to breakage of the tearportion 24 is prevented from spreading to the hinge portion 26 during aninitial period when the bag body of the air bag is expanding.

Moreover, since the length of the groove 76 at the rear side of theautomotive vehicle is longer than the length of the groove 74 at thefront side of the automotive vehicle, the expansion degree of the reardoor portion 20B at the rear side of the automotive vehicle (at the sideof the occupant) can be made large, so that the air bag body 18 can besmoothly expanded. Further, the angle of expanding the door (the angleof bending the door) can be easily adjusted by changing the length orthe depth of the grooves 74 and 76.

Further, in this seventh embodiment, as shown in FIG. 22, the groove 74at the front side of the automotive vehicle and the groove 76 at therear side of the automotive vehicle, respectively, are formed one eachin the air bag door portion 20; however, the number and the formedposition of each of the grooves 74 and 76 are not limited to this, andas shown in FIG. 23A, the grooves 74 and 76 can be separated into aplurality of short grooves 82 and 84, respectively. Further, as shown inFIG. 23B, a position of the separated groove 82 may be near the endportion 80. Still further, in correspondence to a curve of the outerappearance of the air bag door portion 20, the grooves 82 and 84 may beformed in a circular arc shape expanding in a direction in which theymutually move apart from each other as shown in FIG. 23C, or a circulararc shape expanding in a direction in which they mutually move close toeach other as shown in FIG. 23D. Accordingly, the resin fluidity can beprevented from being lowered during injection molding, the door hingeportion can be made bendable along the round of the upper surface of theproduct of the door hinge portion when the door portion is bent andopened, and the door hinge portion can be prevented from breaking.Further, the cross-sectional shape of the grooves 74 and 76 is notlimited to the U shape, and other shapes such as a V shape may beemployed. Still further, the tear line 24 is not limited to the H shape,a tear line 24 having a C shape as shown in FIG. 23E and a tear line 24having an X shape as shown in FIG. 23F may be employed. In this case,reference numeral 85 in FIG. 23F denotes a separated groove.

Next, an eighth embodiment of a interior member for an automotivevehicle having an air bag door portion will be described below withreference to FIGS. 24 to 28.

In this case, the same reference numerals are attached to the sameelements as those in the first embodiment, and an explanation thereofwill be omitted.

As shown in FIG. 24, a cross section of the thin portion 24 is formed ina V shape, and as shown in FIG. 26, a height h of the V shape in thethin portion 24 is set to a range not more than the general thickness ofthe air bag door portion, for example, 0<h≦5 mm. Here, in a case whereinthe general further increased. Then, the vicinity of the distal end (abottom portion) 24A corresponds to the tear portion when the air bagdoor portion is expanded, and a resin fluidity boundary 25 between theresin constituting the front door portion 20A of the air bag doorportion 20 and the resin constituting the rear door portion 20B is setnear the distal end 24A.

Next, a method of forming the instrument panel in accordance with thisembodiment will be described in detail.

First, as shown in FIG. 26, a resin is injected into an upper mold 130which is a mold at an outer appearance side of the instrument panel andinto a cavity for the upper mold 130 and a lower mold 132 from apredetermined different gate G1 or a gate G2 (refer to FIG. 25) so as tomold the front door portion 20A of the air bag door portion 20, andfurther, a resin is injected from the gate G1 or the gate G2 so as tomold the rear door portion 20B. At this time, as shown in FIG. 26, adistal end 140 of a slide core 140 substantially formed in a triangularshape in cross section is disposed near the upper mold 130 with a slightinitial gap S (0<S≦2 mm) therebetween, thereby substantially separatingthe cavity 134.

In this case, the slide core 140 is arranged within the lower mold 132so as to be movable in directions of moving near to and apart from theupper mold 130 (a direction of an arrow A and a direction of an arrow Bin FIG. 26).

Further, as shown in FIG. 28 which exemplifies a molding condition, atime T2 of starting the injection of the gate G1 is delayed for a timeTS (a start delay time) with respect to a time T1 of starting theinjection of the gate G2. In this way, an adjustment is performed sothat a time lag TL between a time T3 at which the resin of the frontdoor portion 20A injected and fluidized via the gate G1 reaches thedistal end 140 of the slide core 140 and fills the front door portion20A, and a time T4 at which the resin of the rear door portion 20Binjected and fluidized via the gate G2 reaches the distal end 140 of theslide core 140 and fills the rear door portion 20B becomes small. (Thisis in order to prevent a slight disadvantage with respect to ease ofopening and breaking during expansion of the air bag body, due to theshift between the resin fluidizing boundary 25 of the skin layer portionand the distal end 24A of the thin portion 24 becoming large when thetime lag TL becomes large.) Further, at a predetermined point T7 withina range TM between the time T3 at which the resin of the front doorportion 20A reaches the distal end 140 of the slide core 140 and a keeppressure completion time T6, the slide core 140 is instantaneously moved(core back) to a position (a position shown by a solid line in FIG. 27)which corresponds to a position being a predetermined amount L (within arange which is not more than the general thickness of the air bag doorportion, for example, 0<L≦5 mm). Further, when the general thickness ofthe door portion is large, the L may be larger) descended from and in adirection of moving apart from a position (a position shown by adouble-dashed chain line in FIG. 27) near the upper mold 130 in amoment.

Therefore, a space 150 corresponding to the moved volume of the slidecore 140 is generated, a front space 150A of the space 150 is filledwith the resin of the front door portion 20A by the time of the keeppressure completion time T6, and a rear space 150B of the space 150 isfilled with the resin of the rear door portion 20B, so that the dsitalend (the bottom portion) of the thin portion 24 and the resin fluidizingboundary 25 coincide with each other in this portion so as to enter astate shown in FIG. 27. In this case, in FIG. 27, for the purpose ofmaking comprehension easy, the front space 150A and the rear space 150Bfilled with the resin are indicated with different hatching. Further, atime T5 shown in FIG. 28 denotes a keep pressure starting time; afterthe keep pressure completion time T6 has passed, the process moves on tocooling.

Here, setting a keep pressure and a preferable core back timing will bedescribed below.

The keep pressure is generally speaking pressure, that is furtherapplied, after the injection is completed, to the resin injected at apressure of about half the injection pressure and is performed forstabilizing the weight, size and shape of the formed product. Inaccordance with the present embodiment, as shown by a solid line in FIG.33, the keep pressure is decreased, separating into two stagescomprising V1 and V2. Since a value V1 of the first stage of the keeppressure greatly affects the quality of the product, it is difficult tochange it only for a resin combination (weld) strength of the tearportion of the present embodiment, and the degree of freedom is low. Onthe contrary, since a value V2 of the second stage of the keep pressuredoes not greatly affect the quality of the product because of the effectof the first stage of the keep pressure, it is easy to change, and thedegree of freedom is high. Accordingly, the core back timing of theslide core 140 is preferably set to a time after the first stage of thekeep pressure has passed, at which it is hard to generate a poorproduct, that is, during the second stage of the keep pressure.

On the contrary, as is generally known, as factors exerting an influenceupon the melting strength of the resin, there are; the surface pressurebetween the resins, and a resin temperature (the lower the surfacepressure and the resin temperature are, the more the melting strength isdecreased). Accordingly, in accordance with the present embodiment, theinvention is structured such that a break force of the tear portion iscontrolled to a desired value by controlling the surface pressurebetween the resins on the melting surface of the tear portion with thekeep pressure and controlling the resin temperature on the meltingsurface of the tear portion with the core back timing and the thicknessin the periphery of the tear portion.

Next, the points mentioned above will be described in detail.

As shown in FIG. 36, a first resin 180 and a second resin 182 aremutually bonded to each other by being respectively pressed in pressingdirections (a direction shown by an arrow X1 and a direction shown by anarrow X2) with a predetermined force, after the respective meltingsurface temperatures have been previously increased so as the surfacesare in a melting state. With respect to the melting strength of themelting surface 184 between the first resin 180 and the second resin182, based on melting principles, there have been generally known twofactors exerting an influence upon the melting strength, that is, thesurface pressure between the resins of the melting surface 184 and theresin temperature.

Thus, in view of controlling the melting strength of the tear portion inaccordance with the present embodiment, the same thinking can beapplied. That is, after fluidization, in a state wherein solidificationhas began to occur, a control is performed with respect to the bondingportion (the melting portion) of the fluidizing resin, replacing thekeep pressure which is the pressure within the mold relating to thesurface pressure transmitted to the melting surface, with the core backtiming and the thickness in the periphery of the tear, relating to theresin temperature (at which the resin of the melting surface portion iscooled from the melting state in accordance with the time passed) of themelting surface.

For example, in a case wherein the injection pressure from the gate of13.5 Mpa, an injection time of 6 sec, a keep pressure of 6.5 Mpa (afirst step), 5.5 Mpa (a second step), a keep pressure time of 2+7 sec,the same product weight and the same test material are used, as shown inFIG. 37A, the higher the keep pressure, the higher the surface pressuretransmitted to the melting surface, and the tear portion breaking forceincreases. Further, as shown in FIG. 37B, the later the core back timingis set, the longer the time for cooling is, so that the resintemperature of the melting surface is reduced, and the tear portionbreaking force is reduced. Still further, as shown in FIG. 37C, thehigher the height of the V shape is set, that is, the thicker thethickness in the periphery of the tear portion is set, the harder it isto reduce the resin temperature of the melting surface, so that the tearportion break force is increased.

Accordingly, the break strength of the tear portion can be easily andaccurately controlled to a desired value with a combination of the keeppressure, the core back timing and the thickness in the periphery of thetear portion.

Further, when the core back timing is too early in comparison with thefilling completion, the filled resin fluidizes within a space at theunfilled side, and the resin fluidizing boundary is shifted from thebreakage expected portion which depends on the slide core; however, incomparison, in a case wherein the core back timing is set to afterfilling is completed, the resin fluidizing boundary and the breakageexpected portion are prevented from being shifted.

In this case, as shown in FIG. 28, it is preferable to set the core backtiming T7 of the slide core 140 after the first stage of the keeppressure time between the keep pressure starting time (T5) and the keeppressure completion time (T6) which is after the filling of the gates G1and G2, has passed, and it is most preferable to set the core backtiming to a time immediately after the first stage of the keep pressuretime has passed so that the resin temperature is not too low.

Further, as shown by a broken line in FIG. 33, the keep pressure may beseparated and reduced in a plurality of stages of three stages or moreand the core back timing may be set to after the second stage of thekeep pressure. In this case, since the first stage of the keep pressureis reliably performed by setting the core back timing to after thesecond stage of the keep pressure, the weight, size and shape of theformed product can be stabilized, so that generation of poor productscan be reduced.

In accordance with the steps mentioned above, as shown in FIG. 27, thethin portion 24 having the V-shaped cross section can be formed by thedistal end 140A of the slide core 140, and the moved amount L of theslide core 140 is small, so that the resin fluidizing boundary 25 is setat the distal end 24A of the thin portion 24.

Accordingly, in the instrument panel 10 in accordance with the presentembodiment, by setting the resin fluidizing boundary 25 near the coreback area of the slide core 140 which is for forming the thin portion 24as the tear portion when the air bag door portion is expanded, that is,near the distal end 24A of the thin portion 24, the break force of thetear portion can be reduced to a desired value due to thickness controland strength reduction, which is dependent on the resin fluidizingboundary 25. Therefore, since it is not necessary to significantlyreduce the resin thickness (the initial gap S+the slide core strokeamount L) of the tear portion, the quality of the outer appearance isprevented from being lowered, and the line of the tear portion is notseen from the outer appearance side at all, so that heat resistance andaging performance is improved and support and surface rigidity of awhole of the air bag door portion is also improved. Further, since theair bag door portion 20 and the main body portion 22 of the instrumentpanel 10 are molded of the same resin, it is not necessary to paint in aseparate manner in accordance with the materials (two kinds), so thatlow cost can be achieved.

Further, in the method of forming the instrument panel in accordancewith the present embodiment, the resin fluidizing boundary 25 can be setat the core back area of the slide core 140, which is for forming thethin portion 24 as the tear portion when the air bag door portion isexpanded, by a simple method comprising steps of: separating the cavity134 of the air bag door portion as the tear portion, with the slide core140 having the distal end formed in a substantially triangular shape;injecting the resin into each of the separated cavities in this state;and moving back the slide core 140 a small amount L under a condition atabout the time filling of the resin is completed. As a result, sinceconventional equipment can be used, it can be formed at a low cost.Further, since a simple method is employed, high reliability can beachieved in securing a functional quality, and productivity is high.

In the above description, the present invention has been explained indetail with respect to the specified embodiments; however, the presentinvention is not limited to the embodiments mentioned above, and it isobvious for those skilled in the art to modify the embodiments to theother various kinds of embodiments within the scope of the presentinvention. For example, the cross-sectional shape of the tear portion 24may be made into other shapes such as a U shape or the like in additionto the V shape. Further, the present invention can be applied to a doortrim, a center pillar, a garnish, a handle and the like in addition tothe instrument panel.

Further, in the eighth embodiment, the structure is made such that theinitial gap S (0<S≦2 mm) is provided between the distal end 140 of theslide core 140 and the upper mold 130 so as to prevent the distal end140 of the slide core 140 and the upper mold 130 from interfering witheach other, thereby taking into consideration a draw scratch preventionon the mold surface and securing of durability; however, in a casewherein the time lag TL is great, the structure may be made such thatthe initial gap S is set to be 0.1≦S≦0.8 mm and the shift between theresin fluidizing boundary 25 in the skin layer portion and the distalend 24A of the thin portion 24 is increased. In this case, it becomesslightly disadvantageous with respect to ease of opening and breakingwhen the bag body of the air bag is expanded; however, the quality ofthe outer appearance of the tear portion line from the outer appearanceside in the distal end 24A can be improved in the same thickness.Further, the structure may be made such that an initial gap of S=0 isset and the front end 140A of the slide core 140 abuts the upper mold130 as occasion demands.

Further, in the eighth embodiment, the injection start time T2 for thegate G1 is delayed the time TS (the start shift time) with respect tothe injection start time T1 for the gate G2; however, in place of this,the structure may be made such that the injection is first performedfrom the gate G1 in accordance with the positional relation between thegates G1 and G2, and the injection from the gate G2 is delayed the timeTS so as to make the filling interval time (the time lag) TL small.Still further, it is also fine if the time that the resin of the frontdoor portion 20A injected from the gate G1 reaches the distal end 140 ofthe slide core 140 and the time T4 that the resin of the rear doorportion 20B injected from the gate G2 reaches the distal end 140 of theslide core 140 are made about the same, by making the injection starttime T2 for the gate G1 and the injection start time T1 for the gate G2the same.

Still further, an area at which the slide core 140 is provided is thearea which satisfies the expansion performance and is allowed by themold structure, and may be the whole area of the H-shaped thin portion24 as shown in FIG. 29A; however, as shown in FIG. 29B, the area of theslide core 140 may be set to be only the area along the lateral line ofthe H-shaped thin portion 24. Further, as shown in FIG. 29C, the area ofthe slide core 140 may be set to be only the area along the verticalline of the H-shaped thin portion 24. Moreover, as shown in FIGS. 29D to29G, the area of the slide core 140 may be set to be only an extreme oneportion of the H-shaped thin portion 24.

Furthermore, the cross-sectional shape of the thin portion 24 may beformed in an R shape as shown in FIG. 30A or a step shape as shown inFIG. 30B in addition to the V shape.

Moreover, the timing of the core back of the slide core 140 may beperformed during the cooling time after the time T6 as far as the resincan fluidize, not only during a moment in the time between the time T3and the time T6 in FIG. 28. Further, the speed of the core back of theslide core 140 may be an instantaneous speed or a slow speed requiring atime from the time T3 to the time T6. Still further, since the resin ofthe front door portion 20A is filled not only from the gate G1 but alsofrom the gate G2 in a go-round manner, the gate may be single.

Further, the forming method in accordance with the eighth embodiment isnot limited to the air bag door portion of a double-leafed hinged doortype in which the thin portion 24 as shown in FIG. 25 is formed in the Hshape in a plan view, but may be applied to an instrument panel havingan air bag door portion in which the thin portion 24 is formed inanother shape such as a C shape, an X shape or the like in a plan view,and to a method of forming the same.

Further, a range in which the slide core 140 is provided in a casewherein the thin portion 24 is formed in a C shape in a plan view is therange which satisfies expansion performance and which is allowed by themold structure, and may be the whole area of the C-shaped thin portion24 as shown in FIG. 29H; however, as shown in FIG. 29I, the area of theslide core 140 may be set to be only the area along a lateral line ofthe C-shaped thin portion 24. Furthermore, as shown in FIGS. 29J and29K, the area of the slide core 140 may be set to be only an extreme oneportion of the C-shaped thin portion 24.

Further, the forming method in accordance with the eighth embodiment canbe applied to an instrument panel 164 having an air bag door portion inwhich a main body portion 160 and an air bag door portion 162 areintegrally formed by coinjection molding which depends on a slide core163, using different resins for the main body portion 160 and the airbag door portion 162 of the instrument panel, as shown in FIG. 31.

Still further, the forming method in accordance with the eighthembodiment can be applied to an instrument panel 174 having an air bagdoor portion which is integrally assembled with an engaging hook, ascrew or the like after injection molding, using a resin, a main bodyportion 170 and an air bag door portion 172 of a separate instrumentpanel, as shown in FIGS. 32A and 32B.

Further, the forming method in accordance with the eighth embodiment canbe applied to the instrument panel 10 as a so-called skin insert-andskin attachment-type trim member for an automotive vehicle, whichcomprises the base member 60 and the skin 62 for covering the outerappearance 60A of the base member 60, as shown in FIG. 34; in this case,the tear portion 64 is formed along the groove 24 on the skin 62 and itis set so that the skin 62 can be easily broken when the bag body of theair bag is expanded. Otherwise, even when the tear portion 64 is notprovided, local tension is generated at the time of expansion since theair bag door portion is made of the material having great rigidity, sothat the skin 62 is easily broken. Further, as the skin 62 indicatedhere, in a case of the skin insert, in addition to the skin 62 having asingle layer as shown in FIG. 17A, the skin 62 having two layers asshown in FIG. 17B and the skin 62 having three layers as shown in FIG.17C may be used.

Further, in a case of the attachment type, in addition to the skin 62having a single layer as shown in FIG. 18A, the skin 62 with the foamlayer 63 as shown in FIG. 18B may be used.

Still further, the forming method in accordance with the eighthembodiment can be applied to the instrument panel 10 as a so-calledintegral foam type trim member for an automotive vehicle which comprisesthe base member 60, the skin 62 and the foam layer 70 between the basemember 60 and the skin 62, as shown in FIG. 35.

Further, the tear portion 64 formed on the skin 62 as shown in FIGS. 34and 35 may be formed from the reverse face side as well as from theobverse face side. Moreover, the shape of the tear portion 64 is notlimited to a U-shaped groove cross section, but may be other shapes suchas a V-shaped groove cross section, a slit shape or the like.

Further, the present invention may be structured as shown in FIG. 38 bydisposing the protrusions 28 and 30, as the push-up means in accordancewith the first embodiment as shown in FIG. 1, in the instrument panel10, as the trim member for the automotive vehicle in accordance with theeighth embodiment as shown in FIG. 24. Still further, the presentinvention may be structured as shown in FIG. 39 by disposing theprotrusions 28 and 30, as the push-up means in accordance with the firstembodiment as shown in FIG. 1, in the instrument panel 10, as the trimmember for the automotive vehicle having the integrally formed air bagdoor portion in accordance with the applied embodiment of the eighthembodiment as shown in FIG. 34. Further, the present invention may bestructured as shown in FIG. 40 by disposing the protrusions 28 and 30,as the push-up means in accordance with the first embodiment as shown inFIG. 1, in the instrument panel 10, as the trim member for theautomotive vehicle having the integrally formed air bag door portion inaccordance with the other applied embodiment of the eighth embodiment asshown in FIG. 35.

INDUSTRIAL APPLICABILITY

As mentioned above, the trim member for the automotive vehicle havingthe air bag door portion in accordance with the present invention andthe method of forming the same are useful for forming the air bag doorportion of the trim member for the automotive vehicle and the main bodyportion of the trim member for the automotive vehicle by the same resin,and are particularly suitable for decreasing the break force of thebreak portion of the air bag door portion to a desired value withoutreducing the quality of the outer appearance.

What is claimed is:
 1. A method of forming an air bag door portion of atrim member, wherein the air bag door portion has a tear portion and aline of the tear portion is not visible from an outer appearance,comprising: separating a mold into cavities by bringing a slide corehaving a distal end formed in a substantially triangular shape intocontact with the mold; and injecting a resin into each of the separatedcavities while moving said slide core slightly backward at about a timefilling is completed, wherein a break strength of the tear portion canbe controlled with a combination of a keep pressure and a core backtiming.
 2. The method according to claim 1, wherein a main body portionof the trim member and the air bag door portion are formed of the sameresin in accordance with an injection molding.
 3. The method accordingto claim 1, wherein a main body portion of the trim member and the airbag door portion are integrally formed using different resins inaccordance with dual injection molding.
 4. The method according to claim1, wherein a main body portion of a base member and the air bag doorportion are formed using the same resin, with said base member and theair bag door portion covered by a skin.
 5. The method according to claim1, wherein a main body portion of a base member and the air bag doorportion are formed using the same resin, with said base member beingcovered by a skin having a tear portion, and a foam layer being formedbetween said skin and said base member.
 6. The method according to claim1, wherein said core back timing is set to after said filling iscompleted.
 7. The method according to claim 6, wherein said keeppressure is decreased in at least two stages with said core back timingset to after a second stage of the keep pressure.
 8. A method of formingan air bag door portion of a trim member, wherein the air bag doorportion has a tear portion formed in the air bag door portion which isnot visible from an outer appearance with a part of the tear portionlocated at the center of the air bag door portion and at least one forceconcentrating means positioned below the air bag door portion andintegrally provided with a lower surface side of the air bag doorportion, for pushing up at least one side of the air bag door portionlocated on either side of the part of the tear portion located at thecenter of the air bag door portion when a bag body of an air bag isexpanded, comprising: separating a mold into cavities by bringing aslide core having a distal end formed in a substantially triangularshape into contact with the mold; and injecting resin into each of theseparated cavities while moving said slide core slightly backward atabout a time filling is completed, wherein a break strength of the tearportion can be controlled with a combination of a keep pressure and acore back timing.
 9. The method according to claim 8, wherein said coreback timing is set to after said filling is completed.
 10. The methodaccording to claim 9, wherein said keep pressure is decreased in atleast two stages with said core back timing set to after a second stageof the keep pressure.